Introduction

Video-assisted thoracic surgery (VATS) is a minimally invasive surgical technique though effective analgesia remains a challenge. Erector spinae plane block (ESPB) has gained popularity due to its ease and safety of placement. In this study, we evaluated the analgesic efficacy of ESPB in patients undergoing VATS through a propensity score-matched retrospective cohort study. The primary outcome is the total opioid use in the first 12 postoperative hours.

Methods

We used binomial logistic regression to model whether patients received ESPB as a function of age, sex, body mass index (BMI), American Society of Anesthesiologists (ASA) physical status, and surgery type to generate a propensity score for each patient for matching.

Results

After screening 286 patients, 55 patients each in the ESPB and no-block groups were matched. ESPB was associated with a 1.2 mg (95% CI: -2.2 to -0.2) reduction in opioid use in IV hydromorphone equivalents when compared to no block. However, there was no reduction in the 12-hour pain score area under the curve or incidence of complications between the two groups.

Conclusions

ESPB was associated with a modest reduction in total opioid consumption although not a difference in pain score. While its analgesic efficacy may be limited, ESPB could be considered a component of multi-modal analgesia in VATS.

Introduction

Over the last decade, minimally invasive video-assisted thoracic surgery (VATS) has gained prominence over thoracotomy [1]. Compared to thoracotomy, VATS is associated with a number of benefits: reduced postoperative pain [2-4], improved recovery [2,3], reduced morbidity [1-3], and more efficient use of hospital resources through shorter operating time [5] and shorter hospital stays [1-4].

Despite its “minimally-invasive” nature, patients undergoing VATS still experience moderate to severe pain [3,6] due to a multitude of sources, including injury to nerves, soft tissue injury, and irritation from chest drains. Furthermore, poor pain control can lead to pulmonary complications in this population who commonly have pre-existing impaired respiratory status [6]. Moreover, the risk of chronic postsurgical pain was reported as high as 25% in VATS [7,8], which can significantly impair quality of life. Therefore, ensuring adequate pain relief remains a priority even for VATS.

To control the multiple sources of pain associated with VATS, multimodal analgesia including regional anesthesia is routinely offered [9]. While thoracic epidural analgesia (TEA) [10-12] has traditionally been utilized for thoracic surgery, it has a number of disadvantages such as its invasiveness, high failure rate, and demanding technicality [9]. Additionally, TEA is associated with rare but significant complications, such as pneumothorax and spinal cord injuries [13,14]. Other reported complications, including hypotension, urinary retention, and lower limb weakness, may furthermore lead to delayed recovery and prolonged hospital stay [9].

Recently, interfascial plane blocks such as erector spinae plane block (ESPB) and serratus anterior plane block (SAPB) emerged as a popular analgesic modality for VATS due to their ease of placement [15-17], improved safety when compared to TEA [18], and potentially greater effectiveness than routine systemic analgesia alone [19]. The site of action of ESPB remains debated, but it is postulated to target both the dorsal and ventral rami of the thoracic spinal nerves, covering the deep muscles of the back as well. Therefore, ESPB is a promising regional anesthesia in VATS.

Although a few studies have evaluated the analgesic efficacy of ESPB in VATS, the results were inconclusive [20-23]. Therefore, our aim was to determine whether ESPB in patients undergoing VATS is associated with reduced opioid consumption in the first 12 postoperative hours through a retrospective propensity score-matched cohort study.

We presented this study as an abstract at the 2024 Canadian Anesthesiologists’ Society Annual Meeting in June 2024.

Materials & Methods

This single-center retrospective study was approved by the Western University Health Science Research Ethics Board (ID: 112452). Data were extracted from the institution’s electronic medical record and nursing charts by the co-investigators (Xu, Liu, Kim, Wu).

Population

This study includes patients who had undergone VATS procedures at Victoria Hospital, a tertiary academic center in London, Canada, from December 1, 2018, to January 1, 2020. All patients who had VATS with or without ESPB were reviewed for eligibility. Patients included were those aged 18 years or older, with American Society of Anesthesiologists (ASA) physical status I-IV, undergoing unilateral VATS, and receiving either an ESPB or no block. Exclusion criteria included BMI >45, chronic pain conditions, daily opioid use >60 mg of oral morphine equivalents, bilateral surgery, conversion to open thoracotomy, postoperative admission to intensive care unit, neuraxial nerve block or other type of block administration (i.e., not ESPB), and history of malignant hyperthermia.

Anesthesia

Patients in both groups received general anesthesia. Patients were induced with fentanyl 2-3 mcg/kg, lidocaine 1 mg/kg, propofol 1-2 mg/kg, and rocuronium 0.6 mg/kg, followed by intubation, generally with double lumen tube and rarely bronchial blocker. Patients were maintained on an air and oxygen mixture to maintain saturation of 92% and above on sevoflurane. Patients received intraoperative IV hydromorphone with the total amount at the discretion of attending anesthesiologists. We did not include intraoperative opioid use as this information was not readily available. Postoperatively, patients received hydromorphone PCA until chest tubes were removed, usually on postoperative day two.

For those in the ESPB group, patients received preoperative ESPB in the block room 30 minutes before surgical anesthesia. Following 1-2 mg of IV midazolam, ropivacaine 0.5% 20 mL was injected between the periosteum of the T4 transverse process and erector spinae muscle under ultrasound guidance using an in-plane technique. Aside from the ESPB, both groups received the same perioperative care.

Measured outcomes

The primary outcome was the total opioid consumption in IV hydromorphone equivalents, including self-administered PCA and nurse-administered parenteral and oral opioids, in the first 12 postoperative hours. The secondary outcomes included the area under curve (AUC) of the numeric rating scale for pain, assessed hourly in the first 12 postoperative hours, incidence of hypoxia during the first 12 postoperative hours defined by oxygen saturation below 90% with or without supplemental oxygen, duration of post-anesthetic recovery unit (PACU) stay, and the total length of hospital stay. The 12-hour period was chosen as a portion of patients were discharged before 24 hours, and many did not have pain scores and vitals collected between the 12 and 24 postoperative hour period.

Statistical methods

G*Power (version 3.1.9.2; Heinrich Heine University Düsseldorf, Germany) was utilized for power calculation. The sample size was calculated with α=0.05 and β=0.8, using a mean and standard deviation of opioid consumption in the first 12 postoperative hours in intravenous (IV) hydromorphone equivalent to 7.69±3.40 mg based on an internal audit of 20 patients. We considered a 30% change in opioid consumption to be a significant difference. Based on these parameters, 70 patients, 35 in each arm, were required. However, given the nature of a retrospective review, to reduce potential bias, all patients who had VATS with or without ESPB were reviewed for eligibility.

Statistical analysis was done using R (version 4.1.2; R Development Core Team, Vienna, Austria). Pre- and post-match patient demographics, including age, sex, BMI, ASA score, and type of surgery, are presented as median and standard deviation (SD) or numbers and percentages. Propensity score matching was used to deal with potential confounders. We used binomial logistic regression to model the anesthesia modality (general anesthesia vs. block + general anesthesia) as a function of age (<= 65 vs. > 65), sex (biological male vs. female), BMI (<= 40 vs. >40), ASA (2 and 3 vs. 4) and surgery type (wedge and segment resection vs. lobectomy and resection on multiple lobes) to generate a propensity score for each patient. Matching was done using the nearest neighbor method, 1:1 matching without replacement, and a caliper of 0.2 of logit. Unmatched patients were not included in the post-match analysis. The standardized difference in means was calculated for each covariate before and after matching to assess for balance. We considered a difference of <10% a balanced match. Continuous post-match variables were analyzed using Mann-Whitney U tests and categorical variables using Fisher’s exact tests.

Results

Between December 1, 2018, and January 1, 2020, 286 patients were screened, with 170 ultimately meeting the criteria (98 in the no-block group and 72 in the ESPB group). Fifty-five patients in each group were successfully matched (Figure 1).

Figure 1: Flow chart for patient recruitment

ESPB – Erector spinae plane block

Patient demographics of each group before and after the match are noted in Table 1. Before the match, the standardized mean difference (SMD) showed some heterogeneity in age, sex, BMI, and surgery type. After the match, all covariates showed an SMD of less than 10%.

ESPB was correlated with a reduction of 1.2 mg (95% confidence interval (CI): -2.2 to -0.2 mg, p=0.02) in 12-hour opioid use in IV hydromorphone equivalents. E-value, which measures the robustness of the result against unaccounted confounders, for the primary outcome was 1.7 (lower 95% CI: 1.2). There was no associated difference in 12-hour pain score AUC, PACU length of stay, hospital length of stay, or incidence of hypoxia between the two groups (Table 2).

Discussion

Poorly controlled acute pain post VATS can result in chronic postsurgical pain in as high as 25% of patients [7,8]. Therefore, adequate early analgesia is essential in VATS. While our study showed an associated reduction in the first 12-hour opioid consumption in the ESPB group, this reduction was modest and clinically insignificant. This was not unexpected. While the ESPB may target pain mediated by thoracic spinal nerves, irritation of the diaphragm, visceral pleura, and more distant thoracic dermatomes may not be covered by ESPB.

Other studies have demonstrated a more pronounced reduction in postoperative analgesia use within the first 24 hours when compared against with no block group [19,24] or a placebo saline block group [25]. Cifti et. al conducted a prospective randomized study that showed that single-shot ESPB using bupivacaine was associated with consistently lower opioid consumption in the first 24 postoperative hours compared to no block [19]. Two similar randomized control trials using ESPB single-shot ropivacaine also showed reduced sufentanil consumption, both intra- and post-operatively [24,25].

Although we did not observe a difference in the first 12-hour AUC in pain score in our study, Cifti et. al showed that single-shot of bupivacaine was associated with lower passive and active pain scores compared to no block, for the first 24 postoperative hours [19]. Multiple other studies also showed a significant reduction in pain scores with ESPB in comparison to no block, sham, or deep SAPB for at least the first six to eight postoperative hours [24,26-28]. This difference in findings could be due to multiple factors, including variations in ESPB administration (dosing, level, and timing) or pain score measurement.

Moreover, effective analgesia in VATS can promote recovery through early mobilization and reduce postoperative complications [3]. Cifti et. al demonstrated that the use of ESPB is associated with faster postoperative out-of-bed activity compared to no block [19]. ESPB has also been associated with earlier discharge times when compared with sham block [25,27]. Furthermore, patients reported higher satisfaction with ESPB compared to placebo saline blocks [25]. Based on these findings, ESPB appears to improve postoperative recovery, and future studies examining postoperative outcomes in patients undergoing VATS would be warranted.

On the other hand, despite the fact that we and others have shown ESPB to be more effective than no block, the best regional anesthesia technique remains debated. ESPB has been shown to be less effective than thoracic paravertebral blocks and no more effective than intercostal nerve blocks for postoperative morphine consumption [11,20]. A network meta-analysis by Sandeep et. al in 2022 showed that thoracic paravertebral blocks are superior to ESPB in reducing IV morphine use postoperatively [28]. Therefore, further studies comparing ESPB against other regional blocks are needed to reach a consensus.

As a retrospective study, there may be unaccounted confounders. The E-value of 1.7 suggested the data may be weak against unmeasured biases. Self-reported pain scores are also subjective and can vary due to differences in pain tolerance between patients, which may be a confounding variable when evaluating the effectiveness of ESPB. A more standardized alternative could be the QoR-15 score, which is a multilingual postoperative quality of recovery measurement tool validated through a meta-analysis [29]. One important confounder we were not able to balance was intraoperative opioid use. This may contribute to the weak E-value. Due to a significant proportion of patients being discharged between 16 and 24 hours postoperatively, outcomes in and beyond this interval were thus not collected but would otherwise provide important clinical information. In addition, there may have been changes over time in anesthesia and surgical technique that we did not account for. Our study was only conducted using participants from one hospital, which may limit the generalizability of our findings. Since ESPB is a relatively new type of block, further studies should be conducted at centers participating in the use of this technique. Finally, given the time limitations of our data collection, we did not assess functional outcomes such as time until ambulation or chronic pain outcomes.

Conclusions

ESPB is an attractive component of multimodal analgesia for VATS due to its ease of placement and low incidence of complication. Our retrospective propensity score-matched cohort study showed that ESPB was associated with a very modest reduction in postoperative opioid consumption. No difference was detected in the first 12-hour pain score AUC, incidence of postoperative hypoxia, length of PACU stay, or length of hospital stay between the ESPB group and the non-block group. Given a number of emerging paraspinal blocks such as retrolaminar blocks and intertransverse process blocks are gaining popularity, future studies can be directed to compare the analgesic efficacy of such blocks.

References

1. Batchelor TJ, Rasburn NJ, Abdelnour-Berchtold E, et al.: Guidelines for enhanced recovery after lung surgery: recommendations of the Enhanced Recovery After Surgery (ERAS®) Society and the European Society of Thoracic Surgeons (ESTS). Eur J Cardiothorac Surg. 2019, 55:91-115. 10.1093/ejcts/ezy301
2. Klapper J, D’Amico TA: VATS versus open surgery for lung cancer resection: moving toward a minimally invasive approach. J Natl Compr Canc Netw. 2015, 13:162-4. 10.6004/jnccn.2015.0023
3. McCall P, Steven M, Shelley B: Anaesthesia for video-assisted and robotic thoracic surgery. BJA Educ. 2019, 19:405-11. 10.1016/j.bjae.2019.09.002
4. Abouarab AA, Rahouma M, Kamel M, Ghaly G, Mohamed A: Single versus multi-incisional video-assisted thoracic surgery: a systematic review and meta-analysis. J Laparoendosc Adv Surg Tech A. 2018, 28:174-85. 10.1089/lap.2017.0446
5. Cao C, Manganas C, Ang SC, Peeceeyen S, Yan TD: Video-assisted thoracic surgery versus open thoracotomy for non-small cell lung cancer: a meta-analysis of propensity score-matched patients. Interact Cardiovasc Thorac Surg. 2013, 16:244-9. 10.1093/icvts/ivs472
6. Nagahiro I, Andou A, Aoe M, Sano Y, Date H, Shimizu N: Pulmonary function, postoperative pain, and serum cytokine level after lobectomy: a comparison of VATS and conventional procedure. Ann Thorac Surg. 2001, 72:362-5. 10.1016/s0003-4975(01)02804-1
7. Schug SA, Bruce J: Risk stratification for the development of chronic postsurgical pain. Pain Rep. 2017, 2:e627. 10.1097/PR9.0000000000000627
8. Bayman EO, Parekh KR, Keech J, Selte A, Brennan TJ: A prospective study of chronic pain after thoracic surgery. Anesthesiology. 2017, 126:938-51. 10.1097/ALN.0000000000001576
9. Feray S, Lubach J, Joshi GP, Bonnet F, Van de Velde M: PROSPECT guidelines for video-assisted thoracoscopic surgery: a systematic review and procedure-specific postoperative pain management recommendations. Anaesthesia. 2022, 77:311-25. 10.1111/anae.15609
10. Shanthanna H, Moisuik P, O’Hare T, Srinathan S, Finley C, Paul J, Slinger P: Survey of postoperative regional analgesia for thoracoscopic surgeries in Canada. J Cardiothorac Vasc Anesth. 2018, 32:1750-5. 10.1053/j.jvca.2018.01.003
11. Chen N, Qiao Q, Chen R, Xu Q, Zhang Y, Tian Y: The effect of ultrasound-guided intercostal nerve block, single-injection erector spinae plane block and multiple-injection paravertebral block on postoperative analgesia in thoracoscopic surgery: a randomized, double-blinded, clinical trial. J Clin Anesth. 2020, 59:106-11. 10.1016/j.jclinane.2019.07.002
12. Liang XL, An R, Chen Q, Liu HL: The analgesic effects of thoracic paravertebral block versus thoracic epidural anesthesia after thoracoscopic surgery: a meta-analysis. J Pain Res. 2021, 14:815-25. 10.2147/JPR.S299595
13. Cook TM, Counsell D, Wildsmith JA: Major complications of central neuraxial block: report on the third national audit project of the Royal College of Anaesthetists. Br J Anaesth. 2009, 102:179-90. 10.1093/bja/aen360
14. Wang Q, Zhang G, Wei S, He Z, Sun L, Zheng H: Comparison of the effects of ultrasound-guided erector spinae plane block and wound infiltration on perioperative opioid consumption and postoperative pain in thoracotomy. J Coll Physicians Surg Pak. 2019, 29:1138-43. 10.29271/jcpsp.2019.12.1138
15. Finnerty DT, McMahon A, McNamara JR, Hartigan SD, Griffin M, Buggy DJ: Comparing erector spinae plane block with serratus anterior plane block for minimally invasive thoracic surgery: a randomised clinical trial. Br J Anaesth. 2020, 125:802-10. 10.1016/j.bja.2020.06.020
16. Byrne K, Smith C: Human volunteer study examining the sensory changes of the thorax after an erector spinae plane block. Reg Anesth Pain Med. 2020, 45:761-2. 10.1136/rapm-2019-101019
17. Jo Y, Park S, Oh C, et al.: Regional analgesia techniques for video-assisted thoracic surgery: a frequentist network meta-analysis. Korean J Anesthesiol. 2022, 75:231-44. 10.4097/kja.21330
18. Fang B, Wang Z, Huang X: Ultrasound-guided preoperative single-dose erector spinae plane block provides comparable analgesia to thoracic paravertebral block following thoracotomy: a single center randomized controlled double-blind study. Ann Transl Med. 2019, 7:174. 10.21037/atm.2019.03.53
19. Ciftci B, Ekinci M, Celik EC, Tukac IC, Bayrak Y, Atalay YO: Efficacy of an ultrasound-guided erector spinae plane block for postoperative analgesia management after video-assisted thoracic surgery: a prospective randomized study. J Cardiothorac Vasc Anesth. 2020, 34:444-9. 10.1053/j.jvca.2019.04.026
20. Turhan Ö, Sivrikoz N, Sungur Z, Duman S, Özkan B, Şentürk M: Thoracic paravertebral block achieves better pain control than erector spinae plane block and intercostal nerve block in thoracoscopic surgery: a randomized study. J Cardiothorac Vasc Anesth. 2021, 35:2920-7. 10.1053/j.jvca.2020.11.034
21. Hong JM, Kim E, Jeon S, et al.: A prospective double-blinded randomized control trial comparing erector spinae plane block to thoracic epidural analgesia for postoperative pain in video-assisted thoracic surgery. Saudi Med J. 2023, 44:155-63. 10.15537/smj.2023.44.2.20220644
22. Cosarcan SK, Ercelen O: The effectiveness of regional analgesia techniques in thoracoscopic surgeries: a retrospective single-center study. JARSS. 2022, 30:272-7. 10.54875/jarss.2022.49469
23. Sertcakacilar G, Pektas Y, Yildiz GO, Isgorucu O, Kose S: Efficacy of ultrasound-guided erector spinae plane block versus paravertebral block for postoperative analgesia in single-port video-assisted thoracoscopic surgery: a retrospective study. Ann Palliat Med. 2022, 11:1981-9. 10.21037/apm-22-75
24. Liu L, Ni XX, Zhang LW, Zhao K, Xie H, Zhu J: Effects of ultrasound-guided erector spinae plane block on postoperative analgesia and plasma cytokine levels after uniportal VATS: a prospective randomized controlled trial. J Anesth. 2021, 35:3-9. 10.1007/s00540-020-02848-x
25. Yao Y, Fu S, Dai S, Yun J, Zeng M, Li H, Zheng X: Impact of ultrasound-guided erector spinae plane block on postoperative quality of recovery in video-assisted thoracic surgery: a prospective, randomized, controlled trial. J Clin Anesth. 2020, 63:109783. 10.1016/j.jclinane.2020.109783
26. Ekinci M, Ciftci B, Gölboyu BE, Demiraran Y, Bayrak Y, Tulgar S: A randomized trial to compare serratus anterior plane block and erector spinae plane block for pain management following thoracoscopic surgery. Pain Med. 2020, 21:1248-54. 10.1093/pm/pnaa101
27. Shim JG, Ryu KH, Kim PO, et al.: Evaluation of ultrasound-guided erector spinae plane block for postoperative management of video-assisted thoracoscopic surgery: a prospective, randomized, controlled clinical trial. J Thorac Dis. 2020, 12:4174-82. 10.21037/jtd-20-689
28. Sandeep B, Huang X, Li Y, Xiong D, Zhu B, Xiao Z: A comparison of regional anesthesia techniques in patients undergoing video-assisted thoracic surgery: a network meta-analysis. Int J Surg. 2022, 105:106840. 10.1016/j.ijsu.2022.106840
29. Kleif J, Waage J, Christensen KB, Gögenur I: Systematic review of the QoR-15 score, a patient- reported outcome measure measuring quality of recovery after surgery and anaesthesia. Br J Anaesth. 2018, 120:28-36. 10.1016/j.bja.2017.11.013

Abstract

The laryngeal mask airway (LMA) has gained popularity as an airway management device in the perioperative setting due to its ease of use, reduced invasiveness compared to endotracheal intubation, and lower incidence of complications. However, hiccups, though relatively uncommon, can pose a significant challenge during the perioperative period when an LMA is in place. Abrupt movement because of hiccups can lead to delay in surgery as well as interfere with surgical instrumentation. This discussion presents a case where perioperative hiccups occurred with LMA use and explores the management strategies employed.

Introduction

Hiccups or singultus are sudden, involuntary contractions of the diaphragm and external intercostal muscles, followed by the abrupt closure of the glottis, producing the distinctive “hic” sound [1]. In recent scenarios, the laryngeal mask airway (LMA) has gained popularity as an airway device for spontaneous and controlled ventilation, as it helps avoid complications associated with endotracheal intubation. Acute hiccup during sedation or general anesthesia after the use of LMA is a minor yet notable complication that can have several disruptive effects. It may disturb the surgical field, making it difficult for the surgeon to perform precise procedures. Additionally, it can interfere with lung ventilation, potentially compromising the patient’s oxygenation and ventilation status [2]. This condition can also hinder diagnostic procedures, particularly those requiring steady or controlled conditions, such as imaging or endoscopic examinations. While generally not severe, managing acute hiccups promptly is important to prevent these potential complications. This case suggests that using an LMA device may trigger hiccups, with the incidence of LMA-related hiccups being approximately 1%-14% [3].

Case Presentation

We hereby present a case of a 30-year-old female with a height of 160 cm and 55 kg weight, diagnosed with fibroadenoma in her right breast, scheduled for elective excision surgery under general anesthesia. Classic LMA was decided to be used as an airway adjunct. She had no other significant history, chronic medical conditions, prior surgeries, artificial dentures, or drug allergies.

She was physically fit, with a respiratory rate of 18 breaths/minute, pulse rate of 70 beats/minute, and blood pressure of 110/70 mmHg in the sitting position. On auscultation, breath sounds in both lung fields were normal, and no cardiac murmurs were present. Her airway assessment was Mallampati class I, and she was classified under the American Society of Anesthesiologists (ASA) physical status grade I.

All routine laboratory investigations, including complete blood count, renal function test, liver function test, prothrombin time, and international normalized ratio, were normal with normal ECG and chest X-ray. An informed and written consent was obtained from the patient. The patient was kept nil by mouth for 8 hours preoperatively.

All ASA standard monitors in the operating room were connected, showing a body temperature of 36.8°C, pulse rate of 80 beats/minute, noninvasive blood pressure of 110/70 mmHg, and pulse oximeter saturation of 100%. An intravenous cannula of 20G was taken from the left hand, and 500 mL of Ringer’s lactate solution was started.

Premedication with 0.2 mg intravenous glycopyrrolate, 1 mg midazolam, and 2 μg/kg of fentanyl intravenously was done. An oxygen mask was attached at a flow rate of 8 L/minute, and the patient was induced with 2 mg/kg of propofol. A classic LMA of size 3 was inserted, and 20 mL of air was used for inflating the cuff. Anesthesia was maintained with sevoflurane, nitrous oxide, and oxygen. The patient was kept on controlled ventilation, and intraoperative analgesia was achieved with intravenous paracetamol (1 g). The oxygen saturation and pulse rate were continuously monitored. Noninvasive blood pressure was recorded at five-minute intervals during the intraoperative period.

After 20 minutes of induction, the patient suddenly developed hiccups. They continued despite administering 40 mg of propofol in repeated 10 mg boluses. These hiccups disturbed the surgeon’s instrumentation during the procedure. Next injection, 0.5 mg atropine was given intravenously but was not effective. Subsequently, 50 μg of dexmedetomidine was administered intravenously over a 10-minute period, which successfully resolved the hiccups. Following the administration of dexmedetomidine, there was a noted decrease in both heart rate and blood pressure, though this did not exceed 20% of the patient’s baseline values. The surgery then proceeded without further complications for another 25 minutes.

At the end of surgery, a thorough oral suction was performed, and inhalational agents were discontinued. Once the patient was awake and all airway reflexes were restored, the cuff was deflated, and LMA was removed. She was transferred to the recovery room for further observation. Hiccups did not recur for the next three days while she stayed in the hospital.

Discussion

Hiccups can significantly disrupt surgery, so addressing them promptly is crucial. The hiccup reflex arc consists of two limbs: afferent and efferent limbs. The afferent limb consists of vagal, sympathetic chains from T6 to T12 and phrenic nerves that travel to the hiccup center located at the posterolateral part of the medulla oblongata. The efferent pathway is through the motor fibers of the phrenic nerve and the accessory nerve to the diaphragm. Any stimulation along the reflex pathway leads to a hiccup. It also increases the risk of aspiration by creating a pressure gradient across the lower esophageal sphincter, enabling reflux.

Various etiologies of intraoperative hiccups are excessive food and carbonated beverages preoperatively [2] and various anesthetic drugs and techniques used during general anesthesia like methohexital, thiopentone, midazolam, and opioids [4,5]. Propofol is also one of the causes of hiccups, which can be treated with intravenous lidocaine [6]. However, since propofol is usually given with lidocaine for ameliorating pain during injection, it is rarely found to be the causative agent (Table 1) [7].

Bag mask ventilation before induction has pros and cons. On the one hand, it leads to preoxygenation, and on the other, it leads to stomach insufflation, which can cause hiccups due to vagus nerve stimulation. Patients with preexisting conditions like gastroesophageal reflux disease (GERD) and central nervous disorders are also more prone to hiccups.

Patients induced with LMA cause hiccups due to the stimulation of mechanoreceptors. The distal end of a well-seated LMA lies over the proximal esophagus, and the sudden and rapid stretch of mechanoreceptors in the proximal esophagus leads to hiccups. The stimulus for hiccups in intraoperative settings can also be pain at the surgical site and decreased depth of anesthesia [9].

Treatment guidelines are unclear because the reflex arc is incompletely understood, and various possible etiologies exist. The main goal is to disrupt the reflex arc using pharmacological or nonpharmacological methods.

As a lighter plane of anesthesia is one reason for hiccups, we deepened the plane of anesthesia by giving boluses of propofol, but still, hiccups were present.

Acetylcholine is one of the neurotransmitters triggering the reflex arc. Therefore, giving anticholinergics like atropine 0.5 mg intravenously blocks the vagally mediated reflex from LMA insertion and abolishes the efferent arc from the hiccup center [2]. It additionally decreases intraesophageal pressure [3]. In our case, 0.5 mg atropine was unsuccessful in terminating the reflex arc.

In a study by Koteswara and Dubey, dexmedetomidine, a selective alpha-2 adrenergic receptor agonist, was found to abolish hiccups in a similar scenario, implying that sympatholytic drugs abolish intraoperative hiccups [10]. Since atropine was ineffective, we gave dexmedetomidine 1 μg/kg, and the hiccups ceased. There was a slight decrease in heart rate and blood pressure.

Various other modalities can be used in addition to these drugs. For anesthetic agent-induced hiccups, metoclopramide, through its dopamine antagonism and serotonin agonism, seems to be a potent agent for terminating hiccups [8].

Dexmedetomidine offers several advantages over metoclopramide in the management of hiccups. While metoclopramide was traditionally used for treating hiccups due to its dopamine antagonist properties, dexmedetomidine presents unique benefits that may make it preferable.

Sedative, analgesic, and anxiolytic properties

Stimulating presynaptic receptors in sympathetic nerve endings and central postsynaptic receptors inhibits sympathetic activity. Analgesia is achieved by stimulating α2 adrenoreceptors in the spinal cord. This inhibition of sympathetic activity (one of the pathways of the reflex arc in the hiccups pathway), along with analgesic and sedative properties, may have been the reason for suppressing intraoperative hiccups [10].

Reduced risk of adverse neurological effects

Metoclopramide is known to carry risks of extrapyramidal symptoms, especially in young adults who are at higher risk for developing dystonic reactions [11]. Dexmedetomidine, by contrast, lacks these dopamine-blocking effects, which is a significant advantage in younger patients who are more susceptible to these adverse reactions.

GERD patients are, in general, more prone to hiccups, which, in turn, leads to a higher risk of aspiration, so prophylactically proton pump inhibitors should be used. The only Food and Drug Administration-approved treatment is chlorpromazine (25-50 mg) intravenously [12].

Nonpharmacological stomach desiring and nasal airway lubrication with lidocaine lead to pharyngeal stimulation opposite to C2 C3 and terminate hiccups. Lung recruitment, application of 25-30 cm of H₂O continuous positive airway pressure [2], and suboccipital release technique all reduce pressure on the vagus and interrupt reflex arc [2]. Deliberate hypoventilation, where the end-tidal carbon dioxide is targeted at 48 mmHg, also halts hiccups [13]. Stellate ganglion block is a recent technique for intractable hiccups [14].

Conclusions

Intraoperative hiccups are a nuisance for both anesthetists and surgeons. Using classic LMA heightens the chance of aspiration, especially in the absence of a nasogastric tube. Hence, strategies to reduce gastric insufflation, early detection of the cause, and effective management using various drug modalities are the key points to prevent any complications.

Numerous interventions have been suggested for managing hiccups during anesthesia. However, perioperative treatment remains largely based on empirical evidence, with no approach being “evidence-based.” As a result, no definitive recommendations can be made to treat hiccups. In our case, conventional medications and techniques for multimodal management were ineffective, so dexmedetomidine was administered, successfully controlling the hiccups.

References

1. Musumeci A, Cristofori L, Bricolo A: Persistent hiccup as presenting symptom in medulla oblongata cavernoma: a case report and review of the literature. Clin Neurol Neurosurg. 2000, 102:13-7. 10.1016/s0303-8467(99)00058-x
2. Mathew J, Shen S, Liu H: Intraoperative laryngeal mask airway-related hiccup: an overview. Transl Perioper Pain Med. 2020, 7:145-51. 10.31480/2330-4871/103
3. Kanaya N, Nakayama M, Kanaya J, Namiki A: Atropine for the treatment of hiccup after laryngeal mask insertion. Anesth Analg. 2001, 93:791-2. 10.1097/00000539-200109000-00047
4. Marhofer P, Glaser C, Krenn CG, Grabner CM, Semsroth M: Incidence and therapy of midazolam induced hiccups in paediatric anaesthesia. Paediatr Anaesth. 1999, 9:295-8. 10.1046/j.1460-9592.1999.00378.x
5. Liu CC, Lu CY, Changchien CF, Liu PH, Perng DS: Sedation-associated hiccups in adults undergoing gastrointestinal endoscopy and colonoscopy. World J Gastroenterol. 2012, 18:3595-601. 10.3748/wjg.v18.i27.3595
6. Krishnakumar M, Srinivasaiah B, Naik SS, Goyal A: Propofol-induced hiccups in MRI suite treated with dexmedetomidine. Saudi J Anaesth. 2023, 17:450-1. 10.4103/sja.sja_816_22
7. Landers C, Turner D, Makin C, Zaglul H, Brown R: Propofol associated hiccups and treatment with lidocaine. Anesth Analg. 2008, 107:1757-8. 10.1213/ane.0b013e3181853605
8. Prakash S, Sitalakshmi N: Management of intraoperative hiccups with intravenous promethazine. J Anaesthesiol Clin Pharmacol. 2013, 29:561-2. 10.4103/0970-9185.119131
9. Nwagwu CC, Ebirim LN: Postoperative hiccup induced by LMA—a case report with literature review. Open J Anesthesiol. 2014, 4:236-9. 10.4236/ojanes.2014.410035
10. Koteswara CM, Dubey JK: Management of laryngeal mask airway induced hiccups using dexmedetomedine. Indian J Anaesth. 2013, 57:85. 10.4103/0019-5049.108583
11. Fink FM, Bognar M, Hengl P, Paulmichl M, Nofziger C: Case report: metoclopramide induced acute dystonic reaction in adolescent CYP2D6 poor metabolizers. Front Pharmacol. 2023, 14:1201566. 10.3389/fphar.2023.1201566
12. Polito NB, Fellows SE: Pharmacologic interventions for intractable and persistent hiccups: a systematic review. J Emerg Med. 2017, 53:540-9. 10.1016/j.jemermed.2017.05.033
13. Obuchi T, Shimamura S, Miyahara N, Fujimura N, Iwasaki A: CO(2) retention: the key to stopping hiccups. Clin Respir J. 2018, 12:2340-5. 10.1111/crj.12910
14. Lopez DJ, Kumar S: Stellate ganglion block for intractable hiccups secondary to a motor vehicle collision. Cureus. 2023, 15:e37030. 10.7759/cureus.37030

Background

Hypotension during spinal anesthesia occurs due to sympathetic nervous system blockade, resulting in decreased systemic vascular resistance and reduced cardiac output. Due to reduced sympathetic tone, peripheral arterial vasodilatation and blood pooling in lower limbs due to venodilatation occur, reducing preload to the heart and stroke volume. The elderly patients have reduced cardiovascular compensatory mechanisms, increasing the frequency and severity of hypotension due to sympathetic blockade after spinal anesthesia significantly. Vasopressors correct hypotension during the intraoperative period to maintain organ perfusion. Fluids can be administered, and if given excessively, can cause fluid overload and urinary retention. This study aimed to compare the effectiveness of vasopressors, phenylephrine, and ephedrine in maintaining hemodynamic stability intraoperatively through prophylactic infusion after spinal anesthesia in elderly patients for lower limb orthopedic surgeries.

Methodology

A total of 174 elderly patients aged 60 years and above with American Society of Anesthesiologists (ASA) Classification I and II, undergoing lower limb orthopedic surgeries, enrolled in a randomized comparative study, were allocated into three groups: Group P (phenylephrine, n=58) received 250 mcg phenylephrine in 30 ml normal saline using infusion syringe pump, Group E (ephedrine, n=58) received 30 mg ephedrine in 30 ml normal saline using infusion syringe pump, and Group C (control group, n=58) received mephentermine I/V (6 mg bolus) when the fall in blood pressure was below 30% of baseline without any placebo infusion. Hemodynamic parameters (systolic and diastolic blood pressure, mean arterial pressure (MAP), heart rate) at 15, 10, and 5-minute intervals before spinal anesthesia, and at 3, 6, 9, 12, 15, 20, 25, and 30-minute intervals after spinal anesthesia. The need for rescue doses to treat hypotension after spinal anesthesia was recorded.

Result

At all time intervals following spinal anesthesia, Group E reported heart rate and systolic blood pressure better than Groups P and C, significantly. At 3, 6, 9, 12, 15, and 25-minute intervals following spinal anesthesia, the diastolic blood pressure in Group E was enhanced significantly than Groups P and C. The MAP in Group E was substantially higher than in other groups at 3, 6, 15, and 20-minute intervals following spinal anesthesia, which was statistically significant. Compared to Groups P and C, Group E required lesser rescue doses to treat intraoperative fall in hypotension 30% below baseline and lesser events of bradycardia.

Conclusion

Following spinal anesthesia, the preload to the heart is to be maintained with intravenous (crystalloid or colloidal) solutions to maintain cardiac output adequately. Intraoperative use of phenylephrine and ephedrine as a low-dose prophylactic infusion can be used, as it increases both systemic vascular resistance and preload without cardiac stimulation along with intravenous solutions to maintain hemodynamic parameters such as systolic and diastolic blood pressure, MAP, heart rate effectively but preferably ephedrine in elderly patients.

Introduction

Hypotension is frequently observed after induction of spinal anesthesia which is a commonly used regional technique in elderly patients undergoing lower limb orthopedic procedures [1]. It occurs due to reduced cardiac output and peripheral vascular resistance, which raises the possibility of myocardial ischemia. Impaired cerebral auto-regulation during the perioperative period decreases middle cerebral artery velocity [2]. Reducing the spinal dose and the extent of anesthetic spread to the necessary dermatomes decreases the incidence of adverse effects [3]. As crystalloids are frequently ineffective in ameliorating blood pressure, their administration can soon result in circulatory overload and congestive cardiac failure [4].

The elderly are more likely to have comorbid diseases, which increases their risk of hypoperfusion, which is due to hypotension, the primary risk factor for which is hypovolemia [4,5]. Vasopressors such as phenylephrine and ephedrine can be immediately infused into elderly people to prevent hemodynamic abnormalities following spinal anesthesia [6]. More research is to be done to study the efficacy and minimal dose requirement of vasopressors as a prophylactic infusion to maintain hemodynamics in the elderly population.

The objective of this study was to determine the effectiveness of vasopressors such as phenylephrine and ephedrine as a low-dose prophylactic intravenous infusion to study hemodynamic variations in elderly patients immediately after spinal anesthesia and to prevent hypotension and the need for rescue doses to maintain vital parameters in patients aged 60 years and above undergoing lower limb orthopedic surgeries.

Materials & Methods

This study was registered at Clinical Trials Registry-India with link https://ctri.nic.in/Clinicaltrials/login.php under the CTRI/2023/04/051451 registration number. The study time was from May 2023 to August 2024. The study was conducted after receiving approval from the institutional ethical committee of Bijapur Lingayat District Education (BLDE) (Deemed to be University), Shri BM Patil Medical College, Hospital and Research Centre with ethical clearance number BLDE(DU)/IEC/787/2022-23. A total of 174 patients aged 60 years and above belonging to American Society of Anesthesiologists (ASA) grades I and II [7], scheduled for elective lower limb orthopedic surgical procedures under spinal anesthesia, were included in the study. The study excluded patients with infection at the site of injection, uncontrolled hypotension, allergic or hypersensitivity to vasoconstrictors, coagulopathies, sepsis, fixed cardiac output states, uncontrolled hypertension, hypothyroidism, uncontrolled diabetes, untreated or uncontrolled heart failure, pheochromocytoma, on monoamine oxidase inhibitors, tricyclic antidepressants, phenothiazine compounds, recent myocardial ischemia/infarction.

During the pre-anesthetic evaluation, a detailed history and general and systemic examinations were carried out the previous day. A history of any significant medical illness was elicited and medication history was taken. The airway, respiratory system, and cardiovascular system were assessed. Written informed consent was obtained. Routine investigations such as complete blood profile, bleeding time and clotting time, random blood sugar, serological tests, chest X-ray, and 2D echocardiography were performed.

On the day of the surgery, nil per oral status was confirmed. An 18G IV cannula was secured and preloading with Ringer lactate solution (15 ml/kg) was infused. On the operating table, vital monitors such as non-invasive blood pressure (NIBP), electrocardiography (ECG), and pulse oximetry were attached to record baseline heart rate, blood pressure, and SpO2. The patients were positioned in a sitting posture. Using a 25G Quincke spinal needle, a lumbar puncture was done at the L3-4 or L4-L5 interface following skin disinfection and 2% lignocaine infiltration. Premedication was given with midazolam 0.5 mg I/V to alleviate the anxiety of the patients. The groups were intrathecally administered with 0.5% hyperbaric bupivacaine 15 mg I/V. Subsequently, patients were supined and oxygen (5 L/min) was delivered with a face mask. Five minutes after intrathecal injection, sensory blockade of spinal anesthesia was assessed using ice cubes or pinpricks.

Patients were split randomly into three groups. Group P received a low-dose continuous infusion of 30 ml 0.9% normal saline with 250 mcg of phenylephrine for 30 minutes (8.3 mcg/min) immediately following spinal anesthesia using an infusion syringe pump. Group E received a continuous infusion of 30 ml 0.9% normal saline with 30 mg of low-dose ephedrine for 30 minutes (1 mg/min) immediately following spinal anesthesia using an infusion syringe pump. Group C (control) received a bolus of mephentermine 6 mg I/V after spinal anesthesia when required without any placebo infusion. The infusion of treatment medication in Group P and Group E was started immediately after spinal anesthesia at an infusion rate of 60 ml/hour, and infusion was stopped after 30 mins (study period) following induction of spinal anesthesia. NIBP, heart rate, ECG, and percentage of oxygen saturation (SpO2) were monitored. Incidence of hypotension and bradycardia were noted. Hemodynamic parameters were recorded at 15, 10, and 5 minutes prior to spinal anesthesia and for 0, 3, 6, 9, 12, 15, 20, 25 and 30-minute intervals after spinal anesthesia.

The rescue treatment protocol to treat intraoperative hypotension was followed. If the reduction in systolic blood pressure was greater than 30% below baseline, then a bolus dose of phenylephrine 50 mcg I/V or ephedrine 5 mg I/V was given in respective groups. Atropine 0.6 mg I/V was given if the heart rate was less than 50 beats per minute. In the case of hypertension, the ongoing infusion was stopped.

Statistical analysis

Using G*Power Version 3.1.9.4 (Heinrich-Heine-Universitat Dusseldorf, Dusseldorf, Germany) for sample size calculation, the mean arterial pressure (MAP) for control (mean=90, SD=12), phenylephrine (mean=85, SD=12), and ephedrine (mean=84, SD=9) were obtained. This study required a total sample size of 174 (for each group 58, assuming equal group sizes) to achieve a power of 80% for detecting a difference means [7].

The data was entered into a Microsoft Excel sheet and statistical analysis was performed using IBM SPSS Statistics for Windows, Version 20 (IBM Corporation, New York, US). The findings were evaluated using basic statistics, including mean and standard deviation of numerical variables and percentages for categorical variables. To compare categorical variables between the two groups, the chi-square test was used. For groups that were not normally distributed, the Kruskal-Wallis test was performed. All analyses were two-tailed, with a p-value of <0.05, which was considered to be statistically significant.

Results

In the present study, constituting 174 elderly patients aged 60 years and above, 58 in each group were posted for all elective lower limb orthopedic surgeries (such as open reduction and internal fixation of fractures, tendon repairs, soft tissue procedures, arthroplasty, arthroscopic knee surgeries, etc.) to assess the impact of phenylephrine or ephedrine infusion administered intravenously as a prophylactic measure to prevent hypotension and its effect on heart rate. The present study followed The Consolidated Standards of Reporting Trials (CONSORT) guidelines (Figure 1). There was no statistically significant difference in all groups with demographic characteristics such as age (p=0.496), sex (p=1), ASA grades (p=0.197), and body mass index (p=0.271).

Figure 1: CONSORT flow diagram

CONSORT: Consolidated Standards of Reporting Trials; n: Number of patients

The mean systolic blood pressure at different time intervals was plotted for each group (Figure 2). The mean systolic blood pressure at induction (0 mins) of spinal anesthesia was superior in Group P compared to Group E and the control group. It was enhanced in Group E when compared to other groups at 6 (p=0.001), 9 (p=0.001), 12 (p=0.01), 15 (p=0.02), 20 (p=0.001), 25 (p=0.001) and 30 (p=0.002) minute time intervals after spinal anesthesia, which was statistically significant (p<0.05).

Figure 2: Comparison of SBP before and after SA

SBP: Systolic blood pressure; SA: Spinal anesthesia

The mean diastolic blood pressure at different time intervals was plotted for each group (Figure 3). The mean diastolic blood pressure at induction (0 min) of spinal anesthesia was superior in Group P compared to Group E and the control group. It was enhanced in Group E with reference to other groups at 3 (p=0.002), 6 (p=0.002), 9 (p=0.001), 12 (p=0.02), 15 (p=0.001) and 25 (p=0.01) minute time intervals after spinal anesthesia, which was statistically significant (p<0.05).

Figure 3: Comparison of DBP before and after SA

DBP: Diastolic blood pressure; SA: Spinal anesthesia

The mean values of MAP at different time intervals were plotted and the mean MAP was superior in the control group compared to other groups (Figure 4). The mean MAP was enhanced in the ephedrine group in comparison to Group P at 3 (p=0.02), 6 (p=0.017), 15 (0.007), and 20 (0.006) minute time intervals after spinal anesthesia, which was statistically significant (p<0.05).

Figure 4: Comparison of MAP before and after SA

MAP: Mean arterial pressure; SA: Spinal anesthesia

The mean heart rate at different time intervals was plotted for each group (Figure 5). The mean heart rate was superior in Group E in comparison to other groups and was statistically significant (p<0.05) at 3 (p=0.013), 6 (p=0.014), 12 (p=0.001), 15 (p=0.001), 20 (p=0.001), 25 (p=0.001), and 30 (p=0.001) minute time intervals after spinal anesthesia.

Figure 5: Comparison of heart rate before and after SA

SA: Spinal anesthesia

The number and percentage of rescue doses of vasopressors to treat hypotension if it falls below 30% of baseline, given among all groups, were evaluated using the chi-square test and tabulated (Table 1). The obtained p-value of 0.297 was observed to be statistically insignificant.

The number and percentage of atropine I/V to treat bradycardia (heart rate less than 50 beats/min) given among all groups was tabulated and it was observed to be statistically insignificant (Table 2). The atropine I/V required to treat bradycardia was less in Group E than in Group P and the control group.

The present study observed the hemodynamic variations after spinal anesthesia. Results showed that the mean systolic blood pressure (Group E>Group P>Group C), diastolic blood pressure (Group E>Group P>Group C), MAP (Group E=Group P=Group C), and heart rate were better maintained in Group E compared to Groups P and C above baseline blood pressure before induction. Elderly patients with untreated sympathetic block after spinal anesthesia have lower systolic blood pressure, systemic vascular resistance, and mean venous pressure due to decompensated state. Restoring preload to the heart during spinal block should be accomplished by administering sufficient intravenous fluids (8-10 ml/kg). Adequate preloading precludes a decrease in cardiac output and unanticipated cardiac arrests, but excessive fluid administration can lead to fluid overload [8]. A vasopressor should be administered if the systolic blood pressure declines by 25 to 30% baseline value or less than 90 mmHg. Vasopressors are known to cause vasoconstriction by increasing systemic vascular resistance to prevent spinal-induced hypotension (SIH) eventually, thus they are a better choice for maintaining hemodynamics in elderly patients [9]. The alpha-adrenergic agonist phenylephrine is typically linked to reflex bradycardia [10]. It raises blood pressure due to venoconstriction and arterial vasoconstriction. It increases venous tone, venous return (preload), and systemic vascular resistance.

Ephedrine, a mixed-action (alpha and beta) adrenergic agonist, increases the cardiac output and prevents a decrease in heart rate as it causes greater venoconstriction than arteriolar constriction and results in increased venous return (preload) and enhances cardiac output, blood pressure, and heart rate [11].

As per the observed results in the present study, phenylephrine 250 mcg/30 ml and ephedrine 30 mg/30 ml, were both effective in maintaining hemodynamic stability after subarachnoid block. The systolic blood pressure was well maintained in Group E>Group P>Group C following induction of spinal block. The attenuation of systolic blood pressure due to sympathetic blockade was more pronounced within the initial 15 minutes after spinal anesthesia and well optimized by Group E compared to Groups P and C.

The diastolic blood pressure was enhanced in Group E>Group P>Group C. The MAP was observed to be equally maintained above and at baseline in all groups (Group P=Group E=Group C). However, the initial drop in MAP following the spinal block was better optimized in the ephedrine group. Zunic et al. reported the impact of phenylephrine or ephedrine infusion following spinal anesthesia on hemodynamics in elderly patients for orthopedic surgeries. They observed that cardiac index, MAP, and heart rate were better in Group E than in Groups P and C [7]. Conversely, Abbasivash et al. found that the MAP, systolic and diastolic blood pressures, and the frequency of hypotension were all considerably reduced in the phenylephrine group after spinal anesthesia, with no apparent difference in heart rate among phenylephrine and ephedrine groups. Less vasopressor use was observed in the phenylephrine group [12]. In this study, less vasopressor rescue dose was required to treat hypotension in Group E compared to Groups P and C. Mon et al. demonstrated that Groups P and E achieved good systolic blood pressure, but ephedrine increased cardiac output in comparison to phenylephrine in parturients [13]. Asokan et al. concluded that ephedrine 6 mg and phenylephrine 100 mcg did not differ in their effectiveness in treating hypotension during subarachnoid block for cesarean section. However, maternal bradycardia was more in the phenylephrine group, with equal incidence of fetal acidosis in the study groups [14]. In this study, both ephedrine and phenylephrine were effective in maintaining hemodynamics and considerably better in the ephedrine group. The incidence of bradycardia was also less in the ephedrine group compared to other groups.

The heart rate in the present study was maintained better in Group E>Group C>Group P. Four patients in the phenylephrine group were given atropine 0.6 mg I/V in response to bradycardia, whereas in the Ephedrine group, only two patients had bradycardia. The rescue doses (phenylephrine 50 mcg/ephedrine 5 mg) to maintain systolic blood pressure after a fall of more than 30% below baseline, were required more in the phenylephrine group than in the ephedrine group. Sinha et al. conducted a study and concluded that following subarachnoid block for cesarean delivery, the three vasopressors efficiently preserved arterial blood pressure. When compared to ephedrine and mephentermine, phenylephrine significantly lowered heart rate [15].

Limitations

A larger sample size is required and a multi-centric study is preferred. Invasive blood pressure (IBP) monitoring provides precise monitoring of blood pressure, which was not done in the present study. Cardiac output is not measured which is crucial in determining the effectiveness of vasopressors among the elderly population.

Conclusions

Hypotension following spinal anesthesia, caused by a reduction in stroke volume can be treated with crystalloid or colloidal solutions. Administration of vasopressor agents increases stroke volume and preload by increasing systemic vascular resistance without heart stimulation. Hence, both vasopressors (ephedrine and phenylephrine) can be used along with crystalloid solutions to correct hypotension post-subarachnoid block in elderly patients. Consequently, prophylactic low-dose infusion of ephedrine (0.4-0.5 mg/kg) could be a better vasopressor agent of choice than phenylephrine in maintaining hemodynamic stability in elderly patients aged 60 years and above for lower limb orthopedic surgeries under spinal anesthesia.

References

1. Tarkkila PJ, Kaukinen S: Complications during spinal anesthesia: a prospective study. Reg Anesth. 1991, 16:101-6.
2. Ferré F, Marty P, Bruneteau L, et al.: Prophylactic phenylephrine infusion for the prevention of hypotension after spinal anesthesia in the elderly: a randomized controlled clinical trial. J Clin Anesth. 2016, 35:99-106. 10.1016/j.jclinane.2016.07.020
3. Brull R, Macfarlane AJR, Chan VWS: Spinal, epidural, and caudal anaesthesia. Miller RD, Cohen NH, Erikson LI, Fleisher LA, Wiener JP, Young WL. Miller’s Anaesthesia. 8th ed. United States of America. Elsevier, 2014. 8:1684-720.
4. Tarkkila P, Isola J: A regression model for identifying patients at high risk of hypotension, bradycardia and nausea during spinal anesthesia. Acta Anaesthesiol Scand. 1992, 36:554-8. 10.1111/j.1399-6576.1992.tb03517.x
5. Hartmann B, Junger A, Klasen J, et al.: The incidence and risk factors for hypotension after spinal anesthesia induction: an analysis with automated data collection. Anesth Analg. 2002, 94(6):1521-1529. 10.1213/00000539-200206000-00027
6. Minville V, Fourcade O, Grousset D, et al.: Spinal anesthesia using single injection small-dose bupivacaine versus continuous catheter injection techniques for surgical repair of hip fracture in elderly patients. Anesth Analg. 2006, 102:1559-63. 10.1213/01.ane.0000218421.18723.cf
7. Žunić M, Krčevski Škvarč N, Kamenik M: The influence of the infusion of ephedrine and phenylephrine on the hemodynamic stability after subarachnoid anesthesia in senior adults – a controlled randomized trial. BMC Anesthesiol. 2019, 19:207. 10.1186/s12871-019-0878-4
8. Critchley LA: Hypotension, subarachnoid block and the elderly patient. Anaesthesia. 1996, 51:1139-43. 10.1111/j.1365-2044.1996.tb15051.x
9. Biricik E, Ünlügenç H: Vasopressors for the treatment and prophylaxis of spinal induced hypotension during caesarean section. Turk J Anaesthesiol Reanim. 2021, 49:3-10. 10.5152/TJAR.2020.70
10. Rivera R, Antognini JF: Perioperative drug therapy in elderly patients. Anesthesiology. 2009, 110:1176-81. 10.1097/ALN.0b013e3181a10207
11. Becker DE: Basic and clinical pharmacology of autonomic drugs. Anesth Prog. 2012, 59:159-68. 10.2344/0003-3006-59.4.159
12. Abbasivash R, Sane S, Golmohammadi M, Shokuhi S, Toosi FD: Comparing prophylactic effect of phenylephrine and ephedrine on hypotension during spinal anesthesia for hip fracture surgery. Adv Biomed Res. 2016, 5:167. 10.4103/2277-9175.190943
13. Mon W, Stewart A, Fernando R, et al.: Cardiac output changes with phenylephrine and ephedrine infusions during spinal anesthesia for cesarean section: a randomized, double-blind trial. J Clin Anesth. 2017, 37:43-8. 10.1016/j.jclinane.2016.11.001
14. Asokan A, Muthalu A, Ananthy V, et al.: Comparison of intravenous bolus doses of phenylephrine vs ephedrine along with crystalloid co-loading in the prevention of hypotension during spinal anesthesia for caesarean section. Indian J Clin Anaesth. 2021, 8(4):537-542. 10.18231/j.ijca.2021.116
15. Sinha G, Hemalatha S, Gurudatt C L: Effectiveness of intravenous boluses of phenylephrine, ephedrine and mephentermine as vasopressors for management of perioperative hypotension in elective lower segment caesarean section under spinal anaesthesia – a prospective comparative study. Indian J Clin Anaesth. 2020, 7(1):46-53. 10.18231/j.ijca.2020.009